Process of sugar-refining



UNITED STATES ATENT OFFICE.

LOTHAR STERNBERG, OF NEW' YORK, N. Y., ASSIGNOR TO F. O. MATTHIESSEN & \VIECHERS SUGAR REFINING COMPANY, OF JERSEY CITY, NEW JERSEY.

PROCESS OF SUGAR-REFINING.

SPECIFICATION forming part of Letters Patent No. 434,074, dated August 12, 1890.

Application filer" December 21, 1889. Serial No. 334,568. (No specimens.)

To all whom it may concern.-

Be it known that I, LOTHAR STERNBERG, of the city and State of New York, have invented a new and useful Process of Sugar-Refining, of which the following is a specification.

This improvement is intended for employment in the art of refining molasses, sirups,

- and vegetable-j uices, particularly the sirups produced from sugar-cane, which contain glucose; and its object is to get rid of the glucose as a preliminary step to the extraction of the crystallizable sugar, because glucose, when present, prevents a certain proportion of sugar from crystallizing, and also renders the product impure.

The invention consists in boiling a solution of molasses, sirup, or vegetable juice of a density of, say, 10 to 15 Baum, for aperiod of two hours, more or less, after mixing with such solution a quantity of either caustic lime, caustic strontia, or caustic baryta equaling in weight, say, fifteen to thirty per cent. of the weight of the dry sugar plus the weight of the glucose present. By this means the glucose will be decomposed, and the products of such decomposition, by combining with the lime, strontia, or baryta, as the case may be, will form, first, compounds which remain insoluble so long as the solution is alkaline, and which are immediately separated in a filterpress; secondly, compounds which are precipit-ated by treating the solution with carbonic acid in an ordinary blow-up, and are thus removed, and, finally, certain liquid compounds, the presence of which is not injurious, because they do not interfere with the subsequent extraction of the sugar. Vater may be used as the diluent for the molasses, sirup, or vegetable-juice to be treated in such proportion that the solution will not contain more than twenty per cent. of sugar, or the washing-liquids resulting from various processes of sugar-refining may be used instead of wateras, for example, the thin washing-liquid from the filters, or the so-called washing-lye resulting from washing the saccharate of lime obtained by the process of sugar-refinin g described in Letters Patentof the United States No. 277,521, dated May 15, 1883.

As is well known, glucose is readily decomposed, and its products and also crystallizable sugar are capable of forming compounds with lime, strontia, or baryta. Thus in the socalled lime process of refining sugar-liquids of low grade, described in Letters Patent of the United States No. 240,879, dated May 3, 1881, wherein it is sought to precipitate the impurities of the sugar by forming them into insoluble compounds with lime, care is taken to use only a small quantity of lime and to keep the temperature of the solution under treatment down to 120 Fahrenheit or under during thefirst step of the process, so that the glucose present will'not be affected, and the lime compounds will be formed only with the impurities of the sugar.

In the class of processes of refining canesugar in which large percentages of lime, strontia, or baryta are added to the saccharine solution under conditions which lead to the formation of either mono or multi-basic' saccharates of lime, strontia, or baryta, as the case may be, not only is a certain proportion of otherwise crystallizable sugar prevented from crystallizing by the glucose which is originally present, but the saccharate thus produced is rendered impure by the inclusion with it of the compounds resulting from the decomposition of the glucose; hence the importance of the result secured by the present process in the removal of the glucose from the saccharine solution under treatment as the preliminary step to the subsequent extraction therefrom of the crystallizable sugar by any suitable method-as, for example, by either of the so-called lime or strontia processes.

In the present process, even if the glucose is thrown away, more than its equivalent in value is realized from the increased purity of the final product and from the increase in the yield of crystallized sugar due to the absence of the glucose, which has been removed by the preliminary treatment of the solution, as herein described. For this preliminary treatment either lime, strontia, or baryta may be employed in the manner herein set forth; but lime is preferred because of its small cost, and also because it does not attack cyrstaltoo lizable sugar so strongly as caustic strontia or caustic baryta.

In carrying out the present invention, after the saccharine solution containing, say,twcnty per cent, or less, of sugar has been formed, and either before or after the addition to it of the lime, it is heated to the boiling-point. Either quicklime or hydrate of lime may be employed. The quantity of lime will depend upon the quantity of glucose present in the saccharine solution. It is desirable that the quantity of lime shall equal in Weight, say, fifteen to thirty per cent, of the Weight of the sugar plus the Weight of the glucose present, so that there will be more than sufficient lime to decompose all the glucose and form compounds with all the products of such decomposition. After the introduction of the lime and the almost immediately following decomposition of the glucose the solution is kept boiling continuously until the products of such decomposition, by uniting with the lime, form the herein-mentioned compounds. It has usually been found desirable to continue the boiling for a period of about two hours; but of course this period can be varied Without departing from the invent-ion. At the conclusion of this treatment the solution will be found to yield, a precipitate consisting in part of the salts of lime resulting from the destruction of the glucose, in part of any impurities originally contained in the lime employed, and possibly in part of a portion of the lime present. The solution is then run through a filter-press, by which the resulting precipitate is removed, after which the clear solution is run into vats provided With the devices commonly known as blow-ups, and is saturated with carbonic acid until it is only slightly alkaline. The result of the carbonic-acid treatment is that substantially all the remaining impurities present are precipitated with the resulting carbonate of lime. Care must be taken not to supersaturate the solution and thereby cause any part of the precipitate to redissolve. To this end from two to ten one-hundredths of one per cent. of lime must be retained in the solution. If, however, the carbonization has been carried too far, an excess of lime must be added and the carbonic-acid treatmentrepeated until the solution again exhibits a merely slight alkaline reaction. The solution is again run through the filter-presses to complete its separation from the precipitate, and will be found upon examination to be free from glucose and from any of the injurious compounds resulting from the decomposition of the glucose, so that it may be advantageously subjected to further treatment for the extraction of its crystallizable sugar.

\Vhat I claim as my invention is 1. The improvement in the art of refining low-grade sugars, molasses, sirups, or vegetable juices containing glucose, herein described, which consists in boiling the saccharine solution under treatment, together With a suitable quantity of lime or its equivalent, until the glucose present is decomposed and insoluble glucose compounds are formed, and in then separating the said glucose compounds by filtration.

2. The improvement in the art of refining low-grade sugars, molasses, sirups, or vegetable-juices containing glucose, herein described, which consists, first, in boiling the saccharine solution under treatment together with a suitable quantity of lime, or its equivalent, and thereby decomposing the glucose present, and then separating the resulting insoluble glucose compounds by filtration, and, secondly, in treating the remaining solution With acid, and precipitating and removing by a second filtration the resulting lime compounds and the remainingimpurities present, preparatory to subjecting the solution thus freed from glucose and from injurious compounds resulting from the decomposing of the glucose to further treatment for the extraction of the crystallizable sugar therefrom.

LOTHAR STERNBERG.

Witnesses:

THos. WM. CLARKE, A. M. J ONES. 

